1. Field of Invention
The present invention relates to a core, provided with an insulating member. More specifically, the present invention relates to a core insulating member which is integrally molded by synthetic resin.
2. Description of Related Art
Generally, an electric rotating machine, such as an induction motor and a DC motor (including a generator), is widely used as, for example, a power source in industry, vehicles, and other areas.
In the conventional electric rotating machine, as shown in FIGS. 8(a) and 8(b), a distributed-winding stator 11 includes a core 12, a coil 13, and a core insulating member 17. The core 12 includes a yoke 14, a multitude of teeth 15 that protrude from the yoke 14, and a multitude of slots 16 formed between the teeth 15. The opening portion of the slots 16 are narrower than an inner portion (a depth side). The coil 13 is provided in the slot 16.
The coil 13 and the core 12 are insulated by the core insulating member 17 made of insulating paper having a U-shaped cross section. The core insulating member 17 is fixed in the slot 16 of the core 12, and interposed between an inner surface of the slot 16 and the coil 13, thereby insulating the inner surface of the slot 16 and the coil 13. Furthermore, the core insulating member 17 has cuffs 18 at both ends that are folded back and protrude in a brim configuration. An end of the cuff 18 is in contact with a side face 12a of the core 12 that consists of a side face 15a of the tooth 15 and a side face 14a of the yoke 14, and the coil 13 is held above the side face 12a of the core 12 so as to create a creeping distance 1, thereby securing insulation between the core side face 12a and the coil 13.
However, according to such a conventional insulation structure, the folded-back cuff 18 lengthens an axial length of the stator 11 (lateral length in FIG. 8(b)). Therefore, particularly when an electric motor (electric rotating machine) is used as a drive source of a vehicle such as a hybrid vehicle, the axial length of the stator 11 contributes to a vehicle mounting problem. Accordingly, it is preferable that the insulating member is made attachable to the core side face, thereby reducing the axial length of the stator 11.
Maximum output of the electric motor for driving a vehicle such as a hybrid vehicle in a limited space is required, and therefore, an increase in the space factor of a magnet wire in the slot is also required. Accordingly, in addition to attaching the insulating member to the core side face, forming (molding) the insulating member by synthetic resin can be considered.
Conventionally, examples of the core insulating member as described above include those disclosed in Japanese Patent Laid-Open Publication No. 2000-78778 and Japanese Patent Laid-Open Publication No. 2000-125524.
According to Japanese Patent Laid-Open Publication No. 2000-78778, the yoke and the teeth are constituted separately. After the teeth are fitted with coils, the teeth with fitted coils are attached to the yoke. Then, with the assembly framed by a core and a base plate, liquid resin molding material is poured or injected between the coil and the teeth, so that all teeth with fitted coils and the yoke are fixed and intergrated by electric insulating resin. In this case, a groove portion is formed in a longitudinal direction on both peripheral side faces of the coil-fitted portion of the teeth, and resin is appropriately poured between the coil and the teeth through the groove portion.
According to Japanese Patent Laid-Open Publication No. 2000-125524, an insulating layer covering die is formed by a stator core in which a multitude of silicon steel plates are laminated, a core die block with an outer shape to be inserted into a slot of the stator core, a movable die block, a positioning die block, and a fixed die block. Resin is injected into the insulating layer covering die to integrally mold a resin insulating layer. In this case, a die block supporting portion corresponding to the center of the teeth of the stator core is provided, and the stator core is supported by the supporting portion so as to secure a uniform clearance between the die block and an end face of the stator core. Accordingly, the thickness of the resin is made uniform and a non-resin filled portion is eliminated so that the thickness of the insulating layer can be made thin.
According to Japanese Patent Laid-Open Publication No. 2000-78778, coils are fitted to the teeth in a state separate from the yoke; the insulating resin is poured between the coils, the teeth, and the yoke; and the teeth with fitted coils are attached to the yoke. Such a method is not applicable to a structure formed by fitting an insulating member to a core that has the teeth and the yoke integrally formed, before winding the coil around the core. In addition, according to the related art, it is difficult to integrally mold the insulating member on the core end face. Furthermore, according to the related art, the groove portion for securing the flow of resin is formed on both peripheral side faces of the tooth. However, the groove portion reduces the cross-sectional area of the tooth, serving as a magnetic flux path, thereby possibly lowering efficiency.
Meanwhile, according to Japanese Patent Laid-Open Publication No. 2000-125524, with the stator core being used as a part of the die, a thin insulating layer having a uniform thickness is formed on the core end face and the slot peripheral face of the stator core by resin molding. However, particularly in the electric motor which serves as a drive source of a vehicle such as a hybrid vehicle, the diameter of the core (stator) becomes large. Thus, when combined with the fact that the thin insulating layer has a uniform thickness, it becomes difficult to appropriately fill an entire length of the core with resin.
Therefore, the invention provides a core provided with an insulating member that is formed by pouring synthetic resin and a manufacturing method of the same, wherein the synthetic resin can be poured appropriately while a slot space factor and coil insertability are secured.
Specifically, the invention provides a core provided with an insulating member, including the core having a plurality of slots, each slot formed between two teeth protruding from a yoke and having a side face and a bottom face that are formed in a generally flat shape; and the insulating member having a slot portion covering the slot and a core end face portion covering an end face of the core; wherein a core side face of the slot portion is formed in contact with the side face and the bottom face of one of the plurality of slots, a coil side face of the slot portion having two side portions and a bottom portion that are formed in a generally flat shape, and the slot portion of the insulating member has a thick portion in at least one portion that is thicker than other portions.
Furthermore, the invention provides a method of manufacturing a core provided with an insulating member, including using the core as a first die inserting a protruding portion of a second die into each slot of the core; pouring liquefied insulating resin material into a cavity, formned between the protruding portion and each slot, wherein the insulating member is formed by the resin material filling the cavity, a core side face of a slot portion of the insulating member has both side faces and a bottom face formed in a generally flat shape, a coil side face of the slot portion of the insulating member has both side faces and a bottom face formed in a generally flat shape, and the slot portion has a thick portion in at least one portion that is thicker than other portions.
Accordingly, the slot portion of the insulating member has a core side face thereof that runs along a generally linear shape of the core slot, and therefore a magnetic flux path with a large cross-sectional area can be secured without forming a notch and the like on the teeth. Furthermore, the coil side face of the slot portion is also formed in a generally flat shape, and a sufficient slot space factor and coil insertability can be secured. In addition, since the slot portion is provided with a thick portion in at least one portion, a flow path of insulating resin material during molding can be secured, and the resin material fills accurately and securely, thus allowing the insulating member to be formed in an accurate and thin shape. As a result, a space that is occupied by the insulating member can be decreased, thereby reducing the size of an electric rotating machine using the core, and also allowing improvement of reliability with respect to insulation.
In this case, the core may be a stator core or a rotor core, and also includes teeth extending in an outer radial direction as well as in an inner radial direction. Furthermore, the generally flat shape with regard to the slot of the core and the slot portion of the insulating member naturally includes a flat surface formed by a straight line, in addition to including a curve such as an arc or oval with a large curvature radius. In short, the generally flat shape includes shapes that form a substantially straight line connected by a smooth line with no sharp angles.